Acoustic apparatus



Feb. 25, 1936.

C. SCHAPIRA ACOUSTIC APPARATUS Filed July 1, 1953 INVENTOR ATTO R N EY Patented Feb. 25 1936 UNITED STATES PATENT OFFICE ACOUSTIC APPARATUS Germany Application July 1, 1933, Serial No. 678,612

2 Claims.

This invention relates to acoustic apparatus. More particularly it relates to an arrangement for encased loudspeakers.

In loudspeakers known in the art it was customary in mounting a diaphragm surrounded by a metallic supporting skeleton, into its casing or cabinet to use a wooden board or wall adapted to be fitted into the cabinet. The said board consists either of one piece or of a plurality of component segments. The interposition of such a wooden accessory or insert was needed for the reason that modern taste prefers loudspeakers of rectangular or quadrangular shape, while the diaphragm as a general rule is circular.

However, it has been found from practice that the use of wood makes the assembly and mounting essentially more diilicult and more expensive. Moreover, in the course of time wood is subject to more or less warping. This leads to distortion and deformation which, in turn, is attended with mechanical and acoustic imperfections.

According to the invention these drawbacks are obviated by substituting a piece of sheet metal of like size for the wood. The idea of employing metal sheeting for the purpose at first appeared wrong and unsuited on the ground that the tonal effect might be impaired by the production of resonance. Actual experiments, however, have demonstrated that no impairment of the acoustic rendition is caused by the use of metallic sheet material in lieu of wood. The metal sheet wall serving for the supporting of the diaphragm may be punched out of a blank, though it could also be built up of segments.

A particularly advantageous arrangement is obtained if the sheet wall as well as the basketlike skeleton or framework is used to support the diaphragm to which, as a general rule, the magnetic system is attached, are made integral, 1. e., of one piece. material is incurred by omission of the inner disk which is the case when the posterior wall is made of a single piece.

The drawing shows exemplified embodiments of the idea of the invention. Fig. 1 illustrates an approved form and. Fig. 2 illustrates a modification.

This means that no loss of In Fig. l the wall supporting the diaphragm skeleton or framework is built up of segments which for reinforcement are provided with elongated corrugations 2 pressure formed therein. The screw holes 3 serve for attaching the diaphragm skeleton and screw holes 4 for securing the segmental parts of the case.

Instead of building the sheet wall of constituent segments, it is also feasible to make it of a single piece. In order to eliminate the waste of material associated with punching out the center piece it is convenient to form the diaphragm skeleton serving to support the diaphragm as well as the driving system out of the latter directly, so that the skeleton of the diaphragm and the supporting wall are made of one piece. Hence, working processes tending to render manufacture more costly, are not required in uniting the diaphragm skeleton and the supporting wall. Fig. 2 shows an embodiment of this kind.

The sheet wall 5 and the skeleton 6 consist of one piece. Attached to the skeleton 6 is the driving system I. The screw holes 8 are provided for securing the supporting wall in the case. The

elongated corrugations 9 for reinforcement are similar to those shown in Fig. 1.

In case resonance points of the sheet wall should impair the reproduction quality, disturbances of this kind may be obviated by applying a lining of felt, cork, or some other vibration deadening 

